1. Technical Field of the Invention
The present invention pertains in general to an apparatus for maintaining real-time busy status information in a telephone network, and more particularly, to a method and apparatus for maintaining real time busy status information for a plurality of telephone extensions in a private branch exchange.
2. Description of Related Art
In the small Private Branch Exchange (PBX) market, an operator station typically includes a "busy lamp field" display for displaying busy status information of all telephone extensions connected to the PBX. The display includes green and red light emitting diodes to indicate whether a particular extension is on-hook or off-hook. The display allows an operator to determine whether the telephone extension is currently engaged in a conversation when attempting to connect a caller to the telephone extension. As the number of telephone extensions supported by the PBX grows, however, implementing the busy lamp field display becomes infeasible due to physical limitations in placing the large number of extension indicators on the display panel. Nevertheless, there remains a demand in the marketplace to provide the busy lamp field functionality. Furthermore, in the computer telephony area there is also a demand to provide busy lamp field functionality to other telephone extensions supported by the PBX such that subscribers do not attempt to place a call to telephone extensions which are already busy.
It would be advantageous therefore, to devise a method and apparatus which provides busy lamp field functionality to both an operator station and to subscribers supported by the PBX regardless of the total number of telephone extensions supported by the PBX.